/*
Find the contiguous subarray within an array (containing at least one number) which has the largest sum.

For example, given the array [−2,1,−3,4,−1,2,1,−5,4],
the contiguous subarray [4,−1,2,1] has the largest sum = 6.

click to show more practice.

More practice:
If you have figured out the O(n) solution, try coding another solution using the divide and conquer approach, which is more subtle.
*/

class Solution {
public:
    int maxSubArray(int A[], int n) {
        int maxsum = 0, cursum = 0;
        for (int i=0; i<n; i++) {
            cursum += A[i];
            if (cursum <= 0) cursum = 0; 
            if (cursum > maxsum) maxsum = cursum;
        }
        // check if there's no positive number
        if (maxsum == 0) {
            maxsum = A[0];
            for (int i=1; i<n; i++) {
                if (A[i] > maxsum) maxsum = A[i];
            }
        }
        return maxsum;
    }
};
